Contents

This problem can be caused by the failure to configure a codec on the dial-peer for a device that places calls over the dial peer. In the example in this document, a device that requires g711ulaw attempts to make a call over a dial peer. The call fails and the caller hears a busy tone.

This first section of this document shows you the Cisco CallManager error message trace for this problem. The second section shows the configuration with a pointer to the missing command. The third section explains how to configure the voice class codec command in order to support multiple codecs on the same dial peer.

Note: This configuration does not have the codec g711ulaw command under the dial-peer. By default, the dial-peer uses g729r8 compression. Any devices that do not use g729r8 compression are not able to complete the call.

In order to fix this, add the codec g711ulaw command under the dial-peer.

In some cases it is necessary to support multiple codecs on a dial peer. Different regions or devices might use different codecs. For example, WAN connections between routers use g729, while Cisco Unity servers use g711 by default. If we know that a call must traverse regions that use different codecs or need to integrate devices that require different codecs, then we need to make sure the dial-peer supports multiple codecs. This section explains how to configure multiple codecs for one dial-peer.